BMW exec foresees the demise of the DCT from the M3

[captainaudio]

I don't think the point of the article was that Automatic Transmissions (DCT or otherwise) are going to go away or that manual transmissions are going to go away. I think what the BMW engineer was saying is that as the performance of conventional planetary gear automatic transmissions has developed to the point where it rivals DCT transmissions and that when the point is reached where the DCT has no performance advantage they will be slowly phased out.

In my opinion the DCTs may be around for a while to cater to a niche market but the DCT will not replace the conventional AT in most cars (BMWs or otherwise).



CA

[mkoesel]

Originally Posted by captainaudio

II think what the BMW engineer was saying is that as the performance of conventional planetary gear automatic transmissions has developed to the point where it rivals DCT transmissions and that when the point is reached where the DCT has no performance advantage they will be slowly phased out.

Maybe so, but assuming he was properly quoted, he sure did not make it sound that way.

In my opinion the DCTs may be around for a while to cater to a niche market but the DCT will not replace the conventional AT in most cars (BMWs or otherwise).

The DCT has already replaced the automatic in some small cars (see Ford Fiesta) due to small efficiency gains, and I could see that trend continuing elsewhere. Performance is only one piece of the equation. If the DCT transmission can continue to both perform better and do so more efficiently, it will have a bright future.

[swamp2]

Ugh so much misinformation here...

Originally Posted by Steveo

Lambo's new car due soon shifts in 50 MS!

http://www.evo.co.uk/news/evonews/25...t_details.html

The M-DCT can shift this fast. BMW has not provided actual numbers but I have tested it myself with an accelerometer. Like mkoesel said other have hit 50 ms as well.

Originally Posted by GhostRideTheWhip

Also, you folks need to drive a PDK equipped Porsche(Cayman S preferably). Makes BMW's M-DCT seem like a thing of the past. I don't know why BMW can't copy what Porsche has done with the PDK and call it a day. Going 75 into a corner, downshift 2 gears as I'm braking and it's like the shift never happened. Car didn't jerk, pull, or hesitate. Simply amazing.

Use S2 or S3, sliky smooth on downshifts. The drivelogic for the M-DCT give you quite a bit of nice customization of the shifting both the auto and manual modes.

Originally Posted by mrad01

Change down - what? How slow is that!!!!

Try to go from 5th to 2nd gear in a hairpin quickly. Suck!!! The downshift is shocking...

This is nothing like the M-DCTs that most of us have. No idea why the one you drove would be so different.

Originally Posted by mrad01

How about reversing out of a tight garage when the engine is cold? That is an experience. Need to be up around 2500rpm to get the auto computer clutch to engage. Bad.

The coldest here in So Cal I have used my DCT is about 40 F. There is some higher rpms used but it is still smooth. Who cares what the software does (it is probably protecting something for you and making it last longer... as long as it works.

Originally Posted by mrad01

DCT auto has quite a bit more development to go before it can be considered "overall" better than the 6MT, but the shifting up speed shows the potential...I'll let all the DCT auto buyers of today do all the R&D and I'll buy one when they are ready.

Pure opinion. Again many here have found their DCT better than any auto or manual. No they are not perfect but in my extensive evaluation and testing I say the only problems with M-DCT are like little tiny pimples on a supermodel.

Originally Posted by mrad01

BTW, all 2008 M3s will need their cranks replaced at some point. It was fixed November 2008. Just go to realoem.com and put in your VIN. Go to the crank assembly and see if the bearings and crank for your model have a new part number and the original numbers STOPPED. Scary.

This dounds like pure speculation. If this was like the E46 case there would be a lot more cars failing. A change in part numbers does not imply a definite failure. There is no recall on this either.

[lve2xlr8]

If the transmission doesn't make the car sideways into second and chirp into third I don't want it

[double_j]

Originally Posted by captainaudio

I don't think the point of the article was that Automatic Transmissions (DCT or otherwise) are going to go away or that manual transmissions are going to go away. I think what the BMW engineer was saying is that as the performance of conventional planetary gear automatic transmissions has developed to the point where it rivals DCT transmissions and that when the point is reached where the DCT has no performance advantage they will be slowly phased out.

In my opinion the DCTs may be around for a while to cater to a niche market but the DCT will not replace the conventional AT in most cars (BMWs or otherwise).


CA

This. Reading comprehension for the win. He is not talking about 6MT vs. DCT. He is talking about DCT vs. conventional automatics and throws in that 6MT will never completely go away. My takeaways:

1.) 6 manual will never completely die, it will have application in sports cars where users value high involvement and as a lower cost transmission choice.

2.) DCT may not be the future transmission of choice because conventional autos are getting so good and because of inherent drawbacks to the DCT setup

[Eau Rouge]

Originally Posted by Eau Rouge

Very interesting report.

MT: "Rumours of my demise are premature."

In the event that a torque converter automatic replaces DCT in the next gen M3, I can only wonder how many will be running back to the timeless MT.

Originally Posted by captainaudio

I think that the article is predicting the demise of the DCT rather than manual transmissions. The torque converters on high performance ATs are out of the picture once the car gets moving and some of the newer designs replace the torque converter with a multi-plate clutch. The shift times of both a "converntional' AT and the DCT are so fast that further improvements are moot. Both types of transmissions are capable of shifting much faster than human reaction time and in fact both are faster than "The Blink of an Eye" whch is about 300-400MS.

I have driven the DCT in both the 335is and the M3 and found it to be an excellent transmission but did not find it to be significantly better than a good AT. IMO a lot the appeal of the DCT is that it does not carry the stigma of being a "Slushbox"



CA

That's what I understood. My MT speaks quote was in reference to a slew of comments that have been posted over many months/years to the effect that MT was going Bye Bye thanks to new technology such as DCT. I think it's fair to say that all bets are off on that happening which is very good news to me.

Originally Posted by double_j

This. Reading comprehension for the win. He is not talking about 6MT vs. DCT. He is talking about DCT vs. conventional automatics and throws in that 6MT will never completely go away. My takeaways:

1.) 6 manual will never completely die, it will have application in sports cars where users value high involvement and as a lower cost transmission choice.

2.) DCT may not be the future transmission of choice because conventional autos are getting so good and because of inherent drawbacks to the DCT setup

There's much to agree with in your post.

What I understood the engineer to be saying in so many words is that the inherent limitations of DCT are such that with BMW looking toward an eight or nine gear configuration the conventional automatic are more suited to those number of gears than DCT, and considering that performance wise the conventional autos have now closed the gap once enjoyed by DCT to a point where there there is no longer a trade off. In short, the conventional auto is a match for DCT yet offer greater flexibility where the number of gears is the subject. And from a supply perspective, BMW would likely enjoy a better price per tranny if it purchased only one flavor of automatic (DCT or conventional auto) for all it units that it wishes to equip with automatic trannies.

[mrad01]

Originally Posted by swamp2

Ugh so much misinformation here...


Pure opinion. Again many here have found their DCT better than any auto or manual. No they are not perfect but in my extensive evaluation and testing I say the only problems with M-DCT are like little tiny pimples on a supermodel.



This dounds like pure speculation. If this was like the E46 case there would be a lot more cars failing. A change in part numbers does not imply a definite failure. There is no recall on this either.

So my pure opinion does match up with your pure opinion so it must be mis information. I see.

Pure speculation you say? You are right, and i am wrong. So if you are right, why the he'll is my car in a million pieces getting a new crank and bearings i wonder? I must be dreaming, this guy knows best. Sorry for getting excited sir. Or do you prefer god?

[SenorFunkyPants]

The appeal of DCTs is that the driver can remain in full and precise control of the shifting process both up and down the box.
If an auto box can provide *exactly* the same driving experience then I don't care what the mechanical process is that provides it.

[mkoesel]

Originally Posted by SenorFunkyPants

The appeal of DCTs is that the driver can remain in full and precise control of the shifting process both up and down the box.
If an auto box can provide *exactly* the same driving experience then I don't care what the mechanical process is that provides it.

+1

I honestly haven't sampled any modern performance oriented automatic transmissions. From what I've read, though, they have gotten very good over the past few years. Still, at the same time DCT technology is improving and the bar is always being set higher as far as performance. I would honestly be very surprised if there exists a traditional auto today that would be a worthy replacement for M-DCT. A few years down the road, that could change. But I will believe it when I see it.

[swamp2]

Originally Posted by mrad01

So my pure opinion does match up with your pure opinion so it must be mis information. I see.

Pure speculation you say? You are right, and i am wrong. So if you are right, why the he'll is my car in a million pieces getting a new crank and bearings i wonder? I must be dreaming, this guy knows best. Sorry for getting excited sir. Or do you prefer god?

It is my deductive analysis of your argument, not my opinion, that shows your reasoning is invalid. Just because some M3 have had engine problems and those problem relate to parts that have been updated by BMW this ABSOLUTELY in no way implies nor proves that ALL M3s with the old part numbers will fail in the same way. If you fail to see the multiple logical fallacies in this argument that's fine. It does not mean it is a sound argument. It also does not warrant sarcastic name calling either. Give it a rest.

[swamp2]

Originally Posted by lve2xlr8

If the transmission doesn't make the car sideways into second and chirp into third I don't want it

Wow, you are kidding right? Have a quick review of dynamic stability control vs. M-DCT drivelogic modes. They are unrelated as is a car's ability to do this vs. its transmission type. M-DCT in S6 with DSC off will provide the exact show-off performance you've described. Of course I do agree that doing this can be awfully fun sometimes...

[swamp2]

Originally Posted by mkoesel

+1

I honestly haven't sampled any modern performance oriented automatic transmissions. From what I've read, though, they have gotten very good over the past few years. Still, at the same time DCT technology is improving and the bar is always being set higher as far as performance. I would honestly be very surprised if there exists a traditional auto today that would be a worthy replacement for M-DCT. A few years down the road, that could change. But I will believe it when I see it.

They are pretty darn close. The IS-F has one of the best and fastest true automatics out there. I have not driven the car myself but from what I understand from various reviews is that is it very close to the M-DCT in manual mode but not as good in automatic mode. Most of that is probably down to software. That being said efficiency, gearing flexibility (ability to design exact desired ratios) as well as shift times all still remain superior in the M-DCT. I want to beat on one myself.

[mkoesel]

Originally Posted by swamp2

gearing flexibility (ability to design exact desired ratios)

That's an interesting point that I hadn't put much thought into. Here you are referring to the interdependency between the different available ratios within a planetary gear set, correct? I wonder how big a factor this is when choosing an M-DCT vs. a traditional automatic. It seems like for a performance car application, it could be a fairly important concern. For that matter, even for an economy car, gear ratios could make a difference in MPG. Maybe that's a big part of the reason that Ford, VW, Fiat, etc. have chose DCT over automatic in some applications?

By the way, swamp, do you know if the Mercedes MCT provides the ability to have two gears engaged at the same time like a DCT does? I have been reading about it, and there is a lot of ambiguity and apparent contradiction between different sources. My initial impression was that they've merely replaced the torque converter with a wet clutch. However, technically speaking automatics have a many internal clutch packs to handle the engagement of the various ratios provided by the planetary sets. What I can't determine for certain is, in the case of the MCT, do these (or other innovations for that matter) allow two gears to be selected at once?

[swamp2]

Originally Posted by mkoesel

That's an interesting point that I hadn't put much thought into. Here you are referring to the interdependency between the different available ratios within a planetary gear set, correct?

Yes, exactly.

Originally Posted by mkoesel

I wonder how big a factor this is when choosing an M-DCT vs. a traditional automatic. It seems like for a performance car application, it could be a fairly important concern. For that matter, even for an economy car, gear ratios could make a difference in MPG. Maybe that's a big part of the reason that Ford, VW, Fiat, etc. have chose DCT over automatic in some applications?

Ultimately I think its one of those things that might seem like it matters more than it should (like torque or final drive ratio, say vs. hp). As a designer I would not want that inflexibility though. It's an advantage but really not a huge one.

Originally Posted by mkoesel

By the way, swamp, do you know if the Mercedes MCT provides the ability to have two gears engaged at the same time like a DCT does? I have been reading about it, and there is a lot of ambiguity and apparent contradiction between different sources. My initial impression was that they've merely replaced the torque converter with a wet clutch. However, technically speaking automatics have a many internal clutch packs to handle the engagement of the various ratios provided by the planetary sets. What I can't determine for certain is, in the case of the MCT, do these (or other innovations for that matter) allow two gears to be selected at once?

I don't know. I know the marketing boys like to cloud the air on this box though. I strongly suspect that it is not like a DCT where you can have 2 gear simultaneously engaged.

[ChrisK]

Originally Posted by swamp2

They are pretty darn close. The IS-F has one of the best and fastest true automatics out there. I have not driven the car myself but from what I understand from various reviews is that is it very close to the M-DCT in manual mode but not as good in automatic mode. Most of that is probably down to software. That being said efficiency, gearing flexibility (ability to design exact desired ratios) as well as shift times all still remain superior in the M-DCT. I want to beat on one myself.

From what I have read online, and saw on Top Gear - the IS-F has too many gears and had a hard time figuring which gear it should be in.

[ns2000x]

Originally Posted by Edward

well, F1s are sequential....a lot more like manuals than DCT to begin with.

The only concerns I have for the future of DCT (huge fan of DCT btw), are longevity/reliability in production cars and capability to handle torque.
But still, the 458 Italia, California and Veyron all use DCT and all of those have good amounts of torque so I'm not sure where that concern stemmed from in the first place.

Also, I have no idea where the notion that DCT is clunky around town came from. It's beyond smooth in all operating modes. The only thing that could be fixed is the software issue of engagement lag when going from any forward gear to reverse. Sometimes the car acts like it's in neutral and just rolls forward when you're already in reverse gear.

You are probably thinking of the early to market DSG's from the VW group that were sized for specific applications and were a concern when tuning the same engine based on the increased torque potential and the associated transmission (i.e. by happenstance the 2.0T standard clutch had a higher torque rating than the DSG clutches).

[captainaudio]

As shift times decrease you eventually reach the point where it does not increase real world performance.

When a car is shifting and is between gears it does not come to a stop it merely stops accelerating. We are talking about shift time of 200 milliseconds or less on both DCT and convetonal planetary AT transmissions, Keep in mind that these shift times can not be accurately measures with a stop watch because the reaction time of the human operator of the stop watch is longer than the time being measured.

Also consider that the blink of an eye is 300-400 milliseconds. Now blink and imagine that an accelerating car stops accelerating and begins to coast to a stop for that amount of time until the next gear is engaged and the car once again begins to accelerate.

What effect will having the gears disengaged for that amount of time have on the cars acceleration? I don't have any statistics but it seems to me that the effect would be negligable.

CA

[jworms]

relevant article:

http://www.autoblog.com/2011/02/07/r...ansmission-re/

According to reports circulating the interwebs, the next-generation Porsche 911 GT3 could lose the choice of a manual altogether, replaced by the PDK dual-clutch transmission.

i, for one, welcome our new DCT overlords.

[swamp2]

Originally Posted by captainaudio

As shift times decrease you eventually reach the point where it does not increase real world performance.

When a car is shifting and is between gears it does not come to a stop it merely stops accelerating. We are talking about shift time of 200 milliseconds or less on both DCT and convetonal planetary AT transmissions, Keep in mind that these shift times can not be accurately measures with a stop watch because the reaction time of the human operator of the stop watch is longer than the time being measured.

Also consider that the blink of an eye is 300-400 milliseconds. Now blink and imagine that an accelerating car stops accelerating and begins to coast to a stop for that amount of time until the next gear is engaged and the car once again begins to accelerate.

What effect will having the gears disengaged for that amount of time have on the cars acceleration? I don't have any statistics but it seems to me that the effect would be negligable.

CA

On the contrary:

A fast MT human can shift in about 300 ms. A typical human won't be as fast. The M-DCT can shift in 50 ms or less (I've measured 30 ms with a accelerometer and data acquisition system). If you look any metric which is the time to get from speed 0 to speed X the shift time savings add right up. If you go from 1st gear to 3rd gear you can save 2*300ms - 2*50ms, which is 0.5 seconds! Faster contests gain even more with more shifts.

From a quarter mile perspective, specifically in the M3, the combined advantage of faster shifts and slightly better gear ratios (more of them as well) is equivalently worth about the same as an effective 20 hp. You can find my extensive posts on this point.

[dexx]

Originally Posted by captainaudio

are capable of shifting much faster than human reaction time and in fact both are faster than "The Blink of an Eye" whch is about 300-400MS.

*facepalm*

I must be bored again.

[SenorFunkyPants]

Originally Posted by swamp2

The M-DCT can shift[........] (I've measured 30 ms with a accelerometer and data acquisition system).

I guess most of that 30ms is used for some sort of torque "smoothing" as I've seen quoted 10ms as the optimum mechanical shift time.

[captainaudio]

Originally Posted by swamp2

On the contrary:

A fast MT human can shift in about 300 ms. A typical human won't be as fast. The M-DCT can shift in 50 ms or less (I've measured 30 ms with a accelerometer and data acquisition system). If you look any metric which is the time to get from speed 0 to speed X the shift time savings add right up. If you go from 1st gear to 3rd gear you can save 2*300ms - 2*50ms, which is 0.5 seconds! Faster contests gain even more with more shifts.

From a quarter mile perspective, specifically in the M3, the combined advantage of faster shifts and slightly better gear ratios (more of them as well) is equivalently worth about the same as an effective 20 hp. You can find my extensive posts on this point.

What I was questioning was how that .5 seconds in faster shift times effects acceleration. In other words lets say that we could program a DCT to shift in either 50ms or 300ms and did a 0-100 run in both modes. How much faster would the time be with the faster shifts?

CA